package com.yan_jiu_sheng.LeetCodeHot100.AC;

import java.util.HashMap;
import java.util.Map;

/**
 * https://leetcode.cn/problems/construct-binary-tree-from-preorder-and-inorder-traversal/description/?envType=study-plan-v2&envId=top-100-liked
 * 参考题解：https://leetcode.cn/problems/construct-binary-tree-from-preorder-and-inorder-traversal/solutions/255811/cong-qian-xu-yu-zhong-xu-bian-li-xu-lie-gou-zao-9
 *
 * @author yulongTian
 * @create 2024-06-15 17:11
 */
public class Test47 {
    public static void main(String[] args) {

    }

    public class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;

        TreeNode() {
        }

        TreeNode(int val) {
            this.val = val;
        }

        TreeNode(int val, TreeNode left, TreeNode right) {
            this.val = val;
            this.left = left;
            this.right = right;
        }
    }

    public TreeNode buildTree(int[] preorder, int[] inorder) {
        int preLen = preorder.length;
        int inLen = inorder.length;
        if (preLen != inLen) {
            throw new RuntimeException("Incorrect input data.");
        }
        Map<Integer, Integer> map = new HashMap<>(preLen);
        for (int i = 0; i < inLen; i++) {
            map.put(inorder[i], i);
        }


        return buildTree(preorder, 0, preLen - 1, map, 0, inLen - 1);
    }

    private TreeNode buildTree(int[] preorder, int preLeft, int preRight, Map<Integer, Integer> map,
                               int inLeft, int inRight) {
        if (preLeft > preRight || inLeft > inRight) {
            return null;
        }
        int rootVal = preorder[preLeft];
        TreeNode root = new TreeNode(rootVal);
        int pIndex = map.get(rootVal);

        root.left = buildTree(preorder, preLeft + 1, pIndex - inLeft + preLeft, map, inLeft, pIndex - 1);
        root.right = buildTree(preorder, pIndex - inLeft + preLeft + 1, preRight,
                map, pIndex + 1, inRight);

        return root;
    }


}
